Automatic gauge control of strip in rolling mill employing backup roll bending

ABSTRACT

The disclosure of the present invention relates to the construction and operation of a rolling mill wherein automatic control of the gauge of the strip being rolled is achieved. More particularly, it relates to a rolling mill provided with mechanisms for bending either or both of the work rolls or backup rolls, including backup roll necks, and thereby control the longitudinal gauge of the material. It provides in the preferred form a four-high rolling mill including means for bending the backup rolls thereof so as to control the thickness of the material along its longitudinal axis. In combination with the backup roll bending mechanism and the usual screwdown mechanism, there is provided a beam so arranged with respect to these two elements that the force of the backup crown control system is self-contained and not imposed upon the mill housing. Use of the beam with respect to both backup rolls in this manner assures that the forces of the backup crown control mechanism, which would otherwise impose additional stretch on the housing, is nullified so that there is less need of continually adjusting the roll gap for automatic gauge control.

United States Patent Stone Morris Denor Stone, Pittsburgh, Pa.

United Engineering and Foundry Company, Pittsburgh, Pa.

22 Filed: Oct. 10, 1969 211 Appl.No.: 865,331

[72] inventor:

[73] Assignee:

[30] Foreign Application Priority Date Oct. 21, 1968 Great Britain ..49,805/68 [52] US. Cl ..72/8, 72/245 [51] int. Cl ..B2lb 37/08 [58] Field of Search ..72/237, 240, 241, 245

[56] References Cited UNlTED STATES PATENTS 1,935,091 11/1933 lverson ..72/245 3,171,305 3/1965 Stone..... ....72/241 3,212,314 10/1965 Sieger.... ....72/225 3,373,588 3/1968 Stone ..72/237 [451 Mar. 28, 1972 3,531,960 10/1970 Stone ..72/8

. Primary Examiner-Milton S. Mehr Attorney-Henry C. Westin [57] ABSTRACT The disclosure of the present invention relates to the construction and operation of a rolling mill wherein automatic control of the gauge of the strip being rolled is achieved. More particularly, it relates to a rolling mill provided with mechanisms for bending either or both of the work rolls or backup rolls, including backup roll necks, and thereby control the longitudinal gauge of the material. it provides in the preferred form a four-high rolling mill including means for bending the backup rolls thereof so as to control the thickness of the material along its longitudinal axis. in combination with the backup roll bending mechanism and the usual screwdown mechanism, there is provided a beam so arranged with respect to these two elements that the force of the backup crown control system is self-contained and not imposed upon the mill housing. Use of the beam with respect to both backup rolls in this manner assures that the forces of the backup crown control mechanism, which would otherwise impose additional stretch on the housing, is nullified so that there is less need of continually adjusting the roll gap for automatic gauge control.

2 Claims, 3 Drawing Figures PATENTEDMAR28 I972 3,651,675

SHEET 1. BF 3 INVENTOR MORE/5 D. STONE ATTORNEY PATENIEBMAR28 I972 3,651,675

' SHEET 2 OF 3 Y I N VE N TOR MOR/P/S 0. 570M:

any W, ATTORNEY PATENTEDMAR28 I972 SHEET 3 BF 3 lllllI-IIIIIIIIIII l N VE NTOR a e/5 .0. .STO/VE CW 8 ATTORNEY AUTOMATIC GAUGE CONTROL OF STRIP IN ROLLING MILL EMPLOYING BACKUP ROLL BENDING In previous mills where backup crown control in connection with a four-high rolling mill has been employed as a means for gauge control with respect to the longitudinal variation of the strip, as illustrated in U.S. Pat. No. 3,531,960 issued Oct. 6, 1970, the pressure or reaction forces of the backup bending mechanism, which in this case are piston cylinder assemblies, were taken by the housing which resulted in a change in the gauge of the strip and required additional correction.

It is an object of this invention to provide a mill construction wherein the forces of the roll bending mechanism are isolated from the housing, thereby not only eliminating the influence of these forces from changing the gauge, but also reducing the range of gauge correction needed.

The preferred embodiment of the present invention is illustrated in the accompanying drawings of which FIG. 1 is an elevational view, partly in section, of a four-high mill illustrating one embodiment of the present invention;

FIG. 2 is an end elevational view of the mill shown in FIG. 1; and

FIG. 3 is a diagrammatical view of the major components of the mill.

With reference to these drawings there is illustrated a fourhigh mill comprising two vertically arranged, spaced-apart housings I1 and 12, the housings having customary windows 13 and 14 into which is received a pair of work rolls 15 and 16, each work roll being backed up in turn by a backup roll 17 and 18, respectively.

As best shown in FIG. 2, the journals of each roll are received in bearing chocks, the work roll chocks being identified by the number 19 and the backup bearing chocks by the number 20. In the customary manner, the work rolls are urged away from each other and against their respective backup rolls by balance piston cylinder assemblies 21 mounted in the lower work roll chocks 19.

With reference now to the upper portion of the mill, it will be noted that between the housings and extending through the windows 13 and 14 there is a horizontally arranged beam 23 which, for brevity, reference will be made to only one side of the mill. The lower surface of the beam, in the vicinity of the chock 20, is provided with a rocker plate 24 which engages a similar rocker plate 25 formed on the top of the adjacent chock. Directly across from the area where the beam engages the chock and on its upper surface, there is provided a raised portion which receives a breaker block 26, the top of the breaker block having a spherical surface which is engaged by a complementary surface formed at the bottom of the screw 27. The screw 27 is received in a nut 28 formed in the housing 11, the screw being rotated by a worm and wheel not specifically shown on the drawings.

Drawing attention now specifically to the beam 23, as shown in FIG. 1, the center is connected to a rod 31, which extends in a vertical direction. To the upper end of the rod 3] there is connected a piston 32 of a piston cylinder assembly 33 mounted on a separator 34 that connects the housings l1 and 12 together at the top of the mill. The piston cylinder assembly 33 is employed to urge the chocks against the beam and the beam against the screws. To this end, the beam at its lower end is provided with opposed downwardly extending hooks 35 which cooperate with projections 35a formed at the tops of the chocks 20, whereby in operation of the piston cylinder assembly 33 the hooks engage the chocks and bring them into contact with the bottom ofthe beam.

Still referring to the tops of the mill, it will be noted that at the outer portion of the housings there is provided at each side of the mill piston cylinder assemblies 36 which, as shown at the left of FIG. 1, receive two pistons 37a and 37b, one extending from the top of the cylinder and the other extending from the bottom.

The lower piston 37b engages a rocker plate 38 carried by the beam 23, the rocker plate being provided with a spherical surface which cooperates with a spherical surface formed at the end of the piston, thereby allowing for any relative movement between the two pieces. The upper piston 37a, as shown best in FIG. 2, is connected to a cross member 39, to the ends of which are connected identically pivotal links 40 which extend downward of the rolls on the outside of the windows 13.

With reference now to the upper backup roll 17, and in still referring to but one side of the mill, it will be noted that outward of its main bearing chock 20, there is provided a second bearing chock 41 which, as shown in FIG. 2, is provided with opposed projecting horizontal wings 42. The lower ends of the links 40 are formed so as to engage the wings 42 of the bearing chock 41 whereby the bending force exerted by the cylinder 36 through the piston 37a is imposed upon the end of the roll 17 causing the center portion of the roll to bend in the direction of the work roll.

It will be appreciated that upon the operation of the cylinder 36 by a control means designed to receive a signal of an adverse longitudinal thickness change in the material being rolled a force is imposed upon the beam 23 by the piston 37b in a direction toward the work roll and a force is imposed upon the roll by the piston 37a which imposes a second force upon the beam in a direction opposite from the first force. Moreover, the lever arm effect of these two forces imposed on the beam are equal. Hence, there is a closed force circuit developed whereby not only are there no reaction forces imposed upon the housings II and 12, but the screws 27 are free from any bending forces.

A generally similar arrangement is provided for the lower backup roll 18, in which connection there is a lower beam 45 which extends between the housings 11 and 12 and through the windows 13 and 14 thereof, this being best shown in FIG. 1 which also shows that the beam carries the bearing chocks 20 of the lower backup roll 18. For completion of the description, it will be noted that the chock 20 is separated from the beam by a series of filler plates 46 which are replaceable so as to compensate for the various diameters of the rolls employed in the mill. This, of course, is quite customary in mill design. FIG. 1 also shows as to one side of the mill the relationship between the beam 45 and the housing 11, wherein the beam rests upon the housing, there being rocker plates 48 provided so as to allow for relative movement between these two elements. Outward of the ends of the beams there are provided on the housings 11 and 12 cylinders 49. The cylinder, in referring to one side of the mill, as in the case of the cylinders 36, is provided with two oppositely arranged pistons 51a and 51b, 51a being the upper piston which engages the lower surface of the beam 45 through a spherical bearing block 52 provided for allowing for relative movement between the beam and the piston 51a. The piston 51b extends downwardly from the cylinder 49 and is connected to a cross member 53, to which are pivotally secured at its outer ends, elongated links 54 extending toward the work roll in such a way as to be clear of the window 13.

Outward of the main bearing chock 20 of the lower backup roll 18 is a second bearing chock 55, the chock of which, as shown in FIG. 2, has horizontal wings 56 engaged by links 54 and through which means the bending force of the piston cylinder assembly 49 is applied to the lower roll 18 in a way to bend the central portion of the roll 18 in a direction of the lower work rolls l6 pursuant to a longitudinal gauge control signal. This arrangement, as in the arrangement provided for the upper backup roll 17, provides a closed force circuit wherein the piston 51a imposes a force on the beam in one direction and the piston 51b imposes an equal, but opposite, force on the beam through the chock 20, whereby the bending forces are self-contained and are not imposed upon the housings 11 and 12.

It will be appreciated that various components of the mill illustrated have not been referred to since they are quite common and that some elements have not been shown, since again they are well known in the art. It will be further appreciated that while the present invention has been illustrated in connection with a four-high mill, it may be used in other types of mills as well as other types of processing equipment, such as rubber and paper calenders.

1 1 l 2 t mill] IL anna] where I 7' t= delivered strip thickness or loaded roll gap (in.)

h,,= no load roll gap (in.)

P total rolling load (No.)

M,,,,,, mill spring constant, comprising housing stretch, screw compression, etc., as well as roll compression and flattening and backup roll inboard neck bending (No/in.) related to P.

F= vertical bending load at each end of backup roll (No.)

M spring constant of mill housing, screw compression,

etc. (Included as a part of M above) (No/in.)

M backup roll spring constant, relating to forces, F, to

roll body displacement (No/in.)

Thus, m P/M mill stretch under rolling load P, i.e., increase in roll gap; and ZFIM decrease in roll gap due to forces F (two rolls).

Due to changes in either h,,, P, or F, the consequent change in gauge is:

Equations 1 and 2 are general equations for which it will now be observed that in using the reaction beams, as shown in FIG. 3, the forces F are self-contained between the backup rolls and their associated beams, i.e., as F changes, there is no change in housing stretch since the stretch in the housing is influenced only by the rolling load p. For the mill of FIG. 1, the above general equation becomes: t= h P[ l/M,,,,,,] 2F[ l/M' MR8] and t: 11+ n|ill] l umnl Thus, the change in I due to changes in F forces is given by: t uuw] F as compared to the general case (without reaction beams) of 1 1 At= 2 A hs: MBURB)] F Thus, it is seen that the present disclosure employs reaction beams or the like wherein the effect of backup roll bending forces is optimized or maximized by nullifying any effect of the backup bending forces on the mill stretch. Accordingly. a change of the forces F to correct for the gauge of the strip will produce the largest possible corrective change in the roll gap.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof.

Iclaim:

1. In a method of effecting a simultaneously longitudinal and transverse gauge control of a strip being rolled in a rolling mill having a housing and two or more rolls comprising the steps of:

setting the no load gap between the rolls of the mill,

determining any adverse change in the longitudinal thickness of the strip being rolled from a desired thickness,

applying a bending force to at least one of the rolls of the mill so as to both displace the body of said one roll to vary its relative position with respect to the other roll and thereby effect a change in the roll gap to bring about a change in the longitudinal thickness of the material being rolled to correct for said adverse change in the longitudinal thickness of the strip and to bend the roll body of said one roll to vary its contour and thereb effect a corresponding change in the shape of the rol gap to bring about a variation in the transverse thickness of the strip,

absorbing the reaction forces of said bending force in a manner that the reaction forces are isolated from said housing.

2. In a method according to claim 1 including the additional steps of:

applying a bending force to said other roll so as to both displace the body of said other roll to vary its relative position with respect to said one roll and thereby effect a change in the roll gap to bring about a change in the longitudinal thickness of the material being rolled to correct for said adverse change in the longitudinal thickness of the strip and to bend the roll body of said other roll to vary its contour and thereby effect a corresponding change in the shape of the roll gap to bring about a variation in the transverse thickness of the strip.

UNITED STATES PATENT OFFICE CETEMQATE OF QOREQTWN Patent 3, 5 75 Dated March 28, 1972 I v N Morris Denor Stone It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 3 line 25, "hsg", first occurrence, should A n n read hsg line 26, BU should read A BU line L O, "rolling load p" should read rolling load P line hit, in equation (14.) "F" should read Signed and sealed this 19th day of December 1972.

(SEAL) Attest 2 EDWARD M.FLETGHER,JR. ROBERT GOTTSCHALK Attesting Officer v Commissioner of Patents FORM (10459) USCOMM-DC B0376-P6Q 9 U.5. GOVERNMENT PRINTING OFFICE I 9.9 0-366-33, I 

1. In a method of effecting a simultaneously longitudinal and transverse gauge control of a strip being rolled in a rolling mill having a housing and two or more rolls comprising the steps of: setting the no load gap between the rolls of the mill, determining any adverse change in the longitudinal thickness of the strip being rolled from a desired thickness, applying a bending force to at least one of the rolls of the mill so as to both displace the body of said one roll to vary its relative position with respect to the other roll and thereby effect a change in the roll gap to bring about a change in the longitudinal thickness of the material being rolled to correct for said adverse change in the longitudinal thickness of the strip and to bend the roll body of said one roll to vary its contour and thereby effect a corresponding change in the shape of the roll gap to bring about a variation in the transverse thickness of the strip, absorbing the reaction forces of said bending force in a manner that the reaction forces are isolated from said housing.
 2. In a method according to claim 1 including the additional steps of: applying a bending force to said other roll so as to both displace the body of said other roll to vary its relative position with respect to said one roll and thereby effect a change in the roll gap to bring about a change in the longitudinal thickness of the material being rolled to correct for said adverse change in the longitudinal thickness of the strip and to bend the roll body of said other roll to vary its contour and thereby effect a corresponding change in the shape of the roll gap to bring about a variation in the transverse thickness of the strip. 